Trichloroethylene (TCE) and 2,6-xylidine, two volatile chemicals, have been separately encapsulated in gelatin-sorbitol microcapsules. These formulations have been shown to provide sufficient stability to the chemicals so that they may be useful in dosed-feed toxicology studies. The objectives of this project are to compare the rates and extents of absorption of neat and microencapsulated chemicals in rats and mice, and to evaluate the feasibility of using microencapsulation as a means of incorporating unstable test chemicals into rodent feed for toxicology studies. The rates and extents of absorption of TCE, prepared either as a suspension of microencapsulated TCE in corn oil or as a solution of neat TCE in corn oil, administered by gavage to male Fischer 344 rats have been studied. Similar studies in B6C3F1 mice are being developed. The toxicity of microencapsulated TCE in rats and mice is being studied.